Optical fibre transmission cables traditionally comprise a set of optical modules, tubular in shape, each consisting of a protective sheath in which one or more optical fibres are housed. All the optical modules are surrounded by an external protective cladding (also referred to as a protective sheath) the purpose of which is to isolate the modules from the external environment. This type of cable generally comprises, in addition to the optical modules, central and/or lateral mechanical reinforcement elements intended to reinforce the mechanical properties of the cable, as well as sealing elements.
In the context of a cable installation for deploying an optical fibre communication network, connections at the cable end or along the length of the cable prove to be necessary in order to be able to connect certain optical fibres to optoelectronic equipments or to other optical fibres belonging to other cables of the network. Such connections require having access to optical fibres contained in the actual structure of the cable as simply and quickly as possible, without risking damaging the optical fibres. This access may take place either at the end of the cable or along the length of the cable (then “optical fibre tapping” is usually referred to).
First of all the external protective cladding is removed over a given length of the cable, as well as the reinforcement and sealing elements thereof, in order to bare the various optical modules containing the optical fibres. It is then necessary to strip one of the modules previously bared by removing the protective sheath made from thermoplastic material that surrounds the optical fibres in order to make access to the latter possible.
This operation may be difficult to perform. Indeed, the length of the module portion to be stripped must be able to be relatively long (typically 0.5 to 5.0 meters) and well controlled, the good rupture strength of the optical fibres must be ensured and the “stops” at the protective sheath at the limits of the stripped portion must be relatively clean.
One known stripping method of the prior art consists of manually tearing the protective sheath of the optical module either between the fingers or using fibres as a support for withdrawing the sheath from the module, for example for access at the cable end.
The stripping may also be done by means of a sharp tool when the material of the sheath proves to have an excessively thick wall or to be too rigid to be manipulatable, what is more, on portions of cables several meters long.
Such methods are generally well suited to optical modules with a rigid structure (that is to say having a very thick protective sheath, typically around 0.40 mm), but are not suitable for optical modules with a flexible or supple structure. Indeed, these flexible structure optical modules consist of a thin thermoplastic sheath (typically less than 0.25 mm), making it difficult to “work”, and a manual tearing between the fingers does not allow easy access to the optical fibres. Tearability of the sheaths of optical modules with a flexible structure is moreover not always possible because of the type of material of which the protective sheath consists. Finally, the use of a cutting tool, such as a knife with a retractable blade (or cutter) for example, would risk damaging the optical fibres, even sheathed, and would require a relatively great intervention time. This solution is therefore not optimum.